Image Pickup Apparatus Phase Difference Autofocus Pixel Readout Control
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Solution Overview
Problem
Existing image pickup apparatuses using contrast detection autofocus are slow due to the need to assess contrast information while moving the lens, making quick autofocus operations difficult, and they often compromise on fine image quality and focus detection precision.
Innovation Solution
An image pickup apparatus with a pixel array and a controller that separates the accumulation periods for different pixel types, allowing for efficient phase difference detection autofocus by sharing a floating diffusion area among adjacent rows and optimizing scanning to prevent signal overlap, thereby enhancing focus detection precision and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contrast detection autofocus is used to achieve focus detection, then focus detection can be performed, but the autofocus operation becomes slow due to the need to assess contrast information while moving the lens
Solution Approach 1:
The pixel array is segmented into multiple rows, with specific rows designated for phase difference detection. This segmentation allows the system to dedicate certain pixels solely to focus detection while others capture image data, enabling simultaneous phase difference measurement without requiring lens movement for contrast assessment.
Solution Approach 2:
The patent implements preliminary action by performing phase difference detection using dedicated pixels that capture light flux information before the main image exposure. The floating diffusion area is prepared and configured in advance to receive and process phase difference signals, allowing focus detection to occur without waiting for lens movement and contrast assessment.
2Adaptability or versatility
If pixels for focus detection are arranged in rows with thinning reading to obtain both image data and focus detection signals, then dual functionality is achieved, but fine image quality and focus detection precision cannot always be obtained
Solution Approach 1:
Different rows of pixels are assigned different functions: some rows are dedicated to phase difference detection with optimized local quality for focus measurement, while other rows are optimized for image capture. This local quality differentiation ensures that focus detection pixels maintain high precision without compromising overall image quality, as each region is optimized for its specific purpose.
Solution Approach 2:
The patent utilizes the vertical dimension by arranging phase difference detection pixels in specific rows that are read out separately from the main image data. This dimensional separation allows independent optimization of readout timing and accumulation periods for focus detection versus image capture, resolving the conflict between dual functionality and precision.
3Measurement precision
If the first pixel outputs signal based on entire exit pupil light flux and the second pixel outputs signal based on partial pupil area light flux, then phase difference detection is enabled, but signal overlap and saturation issues occur when accumulation periods are not properly managed
Solution Approach 1:
The patent implements periodic action by setting distinct accumulation periods for different pixel rows. The controller alternates between accumulating light flux for phase difference detection pixels and image capture pixels in a periodic sequence, ensuring that each pixel type receives appropriate exposure without signal overlap or saturation. This periodic switching maintains signal integrity while enabling precise phase difference measurement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables quick and precise autofocus operations while maintaining high image quality by preventing signal seepage and saturation issues between pixels, improving the overall performance of the image pickup apparatus.
Implementation Method 1
a plurality of pixels each including a photoelectric converter are arranged into a matrix pattern
Data Source
AI summary
An image pickup apparatus including a pixel array including a first pixel that outputs a signal based on a light flux passed through an entire area of an exit pupil, a second pixel that outputs a signal based on a light flux passed through a part of the exit pupil, and a floating diffusion area shared by the plurality of rows adjacent to one another; and a controller that sets a first and a second accumulation periods so as to prevent them from overlapping with each other for a predetermined length of time or longer, when the first pixel read in the first scanning shares the floating diffusion area with the second pixel read in the second scanning, the first and second accumulation periods being periods for the row in which the first and the second pixel are arranged, respectively.